In order to train military personnel, live-fire training villages have been used to prepare such personnel for fighting. During these training exercises, numerous bullets become embedded in the panels of the buildings. Over time, the lead embedded into these non-ricocheting structures starts to corrode and as a result is released into the ground. Because there is significant environmental concern over the release of lead into the ground, barriers have been developed which tend to maintain the lead within the barrier and prevent the lead from leaching out into the surroundings.
In the past, a foamed, fiber-reinforced concrete has been used in non-ricocheting barriers to help maintain the lead within the barriers. This type of concrete has been particularly successful in structural panels for houses in live-fire training villages and in enclosures used for grenade training. Foamed-concrete is thought to be the best type of the bullet-trapping barrier material because it does not burn like wood or rubber, or rot, like wood, and cannot wash away like sand or soil. It is alkaline and retains lead better than wood or rubber.
When bullets containing lead are fired into barriers, the bullets and bullet fragments become lodged in the concrete matrix. The moisture in the barrier reacts with the lead and causes corrosion and dissolution of the lead. The alkalinity of the conventional foamed-concrete decreases and the pH of the water in contact with the bullet fragments may become reduced to the point where the lead and its corrosion products begin to dissolve; Lead particles may spall off from the barriers, and fall to the ground. The spalled materials are subject to corrosion, dissolution, and leaching during precipitation. This may cause significant environmental concern. Thus, there is a need in the art for a foamed concrete bullet barrier which may better retain heavy metals.